Mountain Hardwear Bishop Pass™ Gore-Tex® 0F/-18C

The Mountain Hardwear Bishop Pass Gore-Tex 0F/-18C is the premium version of the standard Bishop Pass winter bag, swapping the plain nylon shell for a waterproof-breathable Gore-Tex membrane while keeping the same EN/ISO 23537 testing to -11°C comfort and -18°C limit. The 650-fill-power goose down is treated hydrophobic here — unlike the non-membrane 0F bag, where the down itself isn't treated — so it copes better with condensation inside a tent or open bivy than a bag relying on shell DWR alone. That membrane comfort and the longer cut (sized to 198cm versus 183cm on the standard version) come with a weight penalty: 1531g against 1420g for the non-Gore-Tex 0F, roughly 110g more. For mountaineers and winter bivouackers sleeping without a tent or under an open shelter, that trade-off buys real protection against down getting wet. A two-way zipper, shaped draft collar, and full-length draft tube round out the feature set, with both a stuff sack and a storage sack included.